Solution processable doped triarylamine hole injection materials

ABSTRACT

Methods for fabricating a solution-processed OLED are provided. The methods include depositing an organic layer comprising mixture of an organic electron acceptor and an organic electron donor to form a layer that is insoluble to a non-polar solvent. Devices containing the organic layer may demonstrate improved lifetime and have a lower operating voltage while maintaining good luminous efficiency.

This application is a national stage application of, and claims priorityto, International Application No. PCT/US2010/028676 filed Mar. 25, 2010,the disclosure of which is hereby expressly incorporated herein byreference in its entirety.

The claimed invention was made by, on behalf of, and/or in connectionwith one or more of the following parties to a joint universitycorporation research agreement: Regents of the University of Michigan,Princeton University, The University of Southern California, and theUniversal Display Corporation. The agreement was in effect on and beforethe date the claimed invention was made, and the claimed invention wasmade as a result of activities undertaken within the scope of theagreement.

FIELD OF THE INVENTION

The present invention relates to organic light emitting devices (OLEDs).More specifically, the present invention relates to methods forfabricating a device containing an organic layer comprising an organicelectron donor and an organic electron acceptor that forms a layerinsoluble to a non-polar solvent, and devices containing the organiclayer.

BACKGROUND

Opto-electronic devices that make use of organic materials are becomingincreasingly desirable for a number of reasons. Many of the materialsused to make such devices are relatively inexpensive, so organicopto-electronic devices have the potential for cost advantages overinorganic devices. In addition, the inherent properties of organicmaterials, such as their flexibility, may make them well suited forparticular applications such as fabrication on a flexible substrate.Examples of organic opto-electronic devices include organic lightemitting devices (OLEDs), organic phototransistors, organic photovoltaiccells, and organic photodetectors. For OLEDs, the organic materials mayhave performance advantages over conventional materials. For example,the wavelength at which an organic emissive layer emits light maygenerally be readily tuned with appropriate dopants.

OLEDs make use of thin organic films that emit light when voltage isapplied across the device. OLEDs are becoming an increasinglyinteresting technology for use in applications such as flat paneldisplays, illumination, and backlighting. Several OLED materials andconfigurations are described in U.S. Pat. Nos. 5,844,363, 6,303,238, and5,707,745, which are incorporated herein by reference in their entirety.

One application for phosphorescent emissive molecules is a full colordisplay. Industry standards for such a display call for pixels adaptedto emit particular colors, referred to as “saturated” colors. Inparticular, these standards call for saturated red, green, and bluepixels. Color may be measured using CIE coordinates, which are wellknown to the art.

One example of a green emissive molecule is tris(2-phenylpyridine)iridium, denoted Ir(ppy)₃, which has the structure:

In this, and later figures herein, we depict the dative bond fromnitrogen to metal (here, Ir) as a straight line.

As used herein, the term “organic” includes polymeric materials as wellas small molecule organic materials that may be used to fabricateorganic opto-electronic devices. “Small molecule” refers to any organicmaterial that is not a polymer, and “small molecules” may actually bequite large. Small molecules may include repeat units in somecircumstances. For example, using a long chain alkyl group as asubstituent does not remove a molecule from the “small molecule” class.Small molecules may also be incorporated into polymers, for example as apendent group on a polymer backbone or as a part of the backbone. Smallmolecules may also serve as the core moiety of a dendrimer, whichconsists of a series of chemical shells built on the core moiety. Thecore moiety of a dendrimer may be a fluorescent or phosphorescent smallmolecule emitter. A dendrimer may be a “small molecule,” and it isbelieved that all dendrimers currently used in the field of OLEDs aresmall molecules.

As used herein, “top” means furthest away from the substrate, while“bottom” means closest to the substrate. Where a first layer isdescribed as “disposed over” a second layer, the first layer is disposedfurther away from substrate. There may be other layers between the firstand second layer, unless it is specified that the first layer is “incontact with” the second layer. For example, a cathode may be describedas “disposed over” an anode, even though there are various organiclayers in between.

As used herein, “solution processible” means capable of being dissolved,dispersed, or transported in and/or deposited from a liquid medium,either in solution or suspension form.

A ligand may be referred to as “photoactive” when it is believed thatthe ligand directly contributes to the photoactive properties of anemissive material. A ligand may be referred to as “ancillary” when it isbelieved that the ligand does not contribute to the photoactiveproperties of an emissive material, although an ancillary ligand mayalter the properties of a photoactive ligand.

As used herein, and as would be generally understood by one skilled inthe art, a first “Highest Occupied Molecular Orbital” (HOMO) or “LowestUnoccupied Molecular Orbital” (LUMO) energy level is “greater than” or“higher than” a second HOMO or LUMO energy level if the first energylevel is closer to the vacuum energy level. Since ionization potentials(IP) are measured as a negative energy relative to a vacuum level, ahigher HOMO energy level corresponds to an IP having a smaller absolutevalue (an IP that is less negative). Similarly, a higher LUMO energylevel corresponds to an electron affinity (EA) having a smaller absolutevalue (an EA that is less negative). On a conventional energy leveldiagram, with the vacuum level at the top, the LUMO energy level of amaterial is higher than the HOMO energy level of the same material. A“higher” HOMO or LUMO energy level appears closer to the top of such adiagram than a “lower” HOMO or LUMO energy level.

As used herein, and as would be generally understood by one skilled inthe art, a first work function is “greater than” or “higher than” asecond work function if the first work function has a higher absolutevalue. Because work functions are generally measured as negative numbersrelative to vacuum level, this means that a “higher” work function ismore negative. On a conventional energy level diagram, with the vacuumlevel at the top, a “higher” work function is illustrated as furtheraway from the vacuum level in the downward direction. Thus, thedefinitions of HOMO and LUMO energy levels follow a different conventionthan work functions.

More details on OLEDs, and the definitions described above, can be foundin U.S. Pat. No. 7,279,704, which is incorporated herein by reference inits entirety.

SUMMARY OF THE INVENTION

A method of fabricating an organic light emitting device is provided.The method comprises providing an electrode, depositing a first organiclayer in contact with the electrode by a solution process, and heatingthe first organic layer to form a layer that is insoluble in a non-polarsolvent. Preferably, the electrode is an anode, and the first organiclayer is deposited in contact with the anode.

The first organic layer comprises an organic electron acceptor and anorganic electron donor having the formula:

A, B, and C are 5 or 6 membered cyclic or heterocyclic rings. R_(A),R_(B), and R_(C) are independent selected from the group consisting ofhydrogen, halogen, alkyl, alkoxy, amino, alkenyl, alkynyl, aryl andheteroaryl. R_(A), R_(B), and R_(C) are optionally fused to A, B, and C.At least two of R_(A), R_(B), and R_(C) contain the structure:

X and Y are independently 5 or 6 membered cyclic or heterocyclic rings.R_(X) and R_(Y) are independently selected from the group consisting ofhydrogen, halogen, alkyl, alkoxy, amino, alkenyl, alkynyl, aryl andheteroaryl. R_(X) and R_(Y) are optionally fused to X and Y. R_(X) andR_(Y) are optionally connected to A and B.

In one aspect, the organic electron donor has the formula:

L₁ represents a substituted or unsubstituted arylene group having 6 to60 carbon atoms forming the aromatic ring, a substituted orunsubstituted fluorenylene group, or a substituted or unsubstitutedheteroarylene group having 5 to 60 atoms forming a ring; Ar₁ and Ar₂each independently represents a substituted or unsubstituted aryl grouphaving 6 to 60 carbon atoms forming the aromatic ring or a substitutedor unsubstituted heteroaryl group having 5 to 60 atoms forming a ring;R′₁ represents a substituted or unsubstituted aryl group having 6 to 60carbon atoms forming the aromatic ring; R′₂ represents a hydrogen atom,a substituted or unsubstituted aryl group having 6 to 60 carbon atomsforming the aromatic ring, a substituted or unsubstituted alkyl grouphaving 1 to 50 carbon atoms, a substituted or unsubstituted alkoxy grouphaving 1 to 50 carbon atoms, a substituted or unsubstituted aryloxygroup having 6 to 50 atoms forming a ring, a substituted orunsubstituted arylthio group having 5 to 50 atoms forming a ring, asubstituted or unsubstituted alkoxycarbonyl group having 2 to 50 carbonatoms, an amino group substituted by a substituted or unsubstituted arylgroup having 6 to 50 carbon atoms forming the aromatic ring, a halogenatom, a cyano group, a nitro group, a hydroxyl group or a carboxylgroup; with the proviso that neither Ar₁ nor Ar₂ contains a fluorenestructure, and that the number of a carbazole structures in the aromaticamine derivative represented by the formula is 1 or 2.

In another aspect, the organic electron donor has the formula:

Z is selected from the group consisting of a substituted orunsubstituted C1-C30 alkylene group, a substituted or unsubstitutedC2-C30 alkenylene group, a substituted or unsubstituted C6-C30 arylenegroup, a substituted or unsubstituted C2-C30 heteroarylene group, and asubstituted or unsubstituted C2-C30 heterocyclic group; each of R′₃,R′₄, R′₅, R′₆, R′₇, and R′₈ is independently selected from the groupconsisting of a hydrogen atom, a substituted or unsubstituted C1-C30alkyl group, a substituted or unsubstituted C1-C30 alkoxy group, asubstituted or unsubstituted C6-C30 aryl group, a substituted orunsubstituted C6-C30 aryloxy group, a substituted or unsubstitutedC2-C30 heterocyclic group, a substituted or unsubstituted C6-C30condensed polycyclic group, a hydroxy group, a cyano group, and asubstituted or unsubstituted amino group, and, alternatively, two ormore adjacent groups among R′₃, R′₄, R′₅, R′₆, R′₇, and R′₈ can beconnected to each other to form a saturated or unsaturated carbocycle;and wherein each of Ar₃ and Ar₄ are independently a substituted orunsubstituted C6-C30 aryl group or a substituted or unsubstituted C2-C30heteroaryl group.

In yet another aspect, the organic electron donor has the formula:

L₀ is any one of o-, p-, and m-phenylene groups which have two, three orfour rings and which have a substituent with the proviso that when L₀ isa phenylene group having four rings, the phenylene group may have anunsubstituted or substituted aminophenyl group somewhere therein, andR₀₁, R₀₂, R₀₃ and R₀₄ are any one of the following groups:

R′₉, R′₁₀, R′₁₁, R′₁₂ and R′₁₃ are each a substituted or unsubstitutedaryl group, and r₁, r₂, r₃ and r₄ are each an integer of 0 to 5 with theproviso that r₁+r₂+r₃+r₄≧1.

In one aspect, the organic electron acceptor is selected from the groupconsisting of:

R₁, R₂, R₃, R₄, R₅, and R₆ are independently chosen from the groupconsisting of hydrogen, halogen, nitrile, nitro, sulfonyl, solfoxide,sulfonamide, sulfonate, trifluoromethyl, ester, amide, straight-chain orbranched C1-C12 alkoxy, straight-chain or branched C1-C12 alkyl,aromatic or non-aromatic (substituted or unsubstituted) heterocyclic,substituted or unsubstituted aryl, mono- or di-(substituted orunsibstituted)aryl-amine, and (substituted orunsubstituted)alkyl-(substituted or unsubstituted)aryl-amine; or whereR₁ and R₂, R₃ and R₄, and R₅ and R₆ combine form a ring structureincluding an aromatic ring, a heteroaromatic ring, or a non-aromaticring, and each ring is substituted or unsubstituted;

Y₁ to Y₄ are independently a carbon atom or a nitrogen atom. R₇ to R₁₀are independently a hydrogen atom, an alkyl group, a substituted orunsubstituted aryl group, a substituted or unsubstituted heterocycle, ahalogen atom, a fluoroalkyl group or a cyano group. R₇ and R₈, and R₉and R₁₀ are independently bonded to form a substituted or unsubstitutedaromatic ring or a substituted or unsubstituted heterocycle. X₁ isselected from the group consisting of:

Y₅ to Y₇ are independently a hydrogen atom, a fluoroalkyl group, analkyl group, an aryl group or a heterocyclic group; and Y₆ and Y₇ mayform a ring;

X₂ is

C(R₂₃) or N, R₁₁ to R₂₃ each independently represent a hydrogen atom, asubstituted or unsubstituted alkyl group having 1 to 30 carbon atoms, asubstituted or unsubstituted alkoxy group having 1 to 30 carbon atoms, asubstituted or unsubstituted aryl group having 6 to 40 carbon atoms, atrialkylsilyl group wherein the alkyl group has 1 to 20 carbon atoms andmay have a substituent, an aryloxy group wherein the aryl group has 6 to40 carbon atoms and may have a substituent, a halogen atom, or a cyanogroup, provided that at least two of R₁₁ to R₂₃ each represent a cyanogroup, a trifluoromethyl group or a fluorine atom and that those of R₁₁to R₂₃, which are adjacent to one another, may be linked together toform a ring structure;

R₂₄ to R₃₉ each independently represent a hydrogen atom, a substitutedor unsubstituted alkyl group having 1 to 30 carbon atoms, a substitutedor unsubstituted alkoxy group having 1 to 30 carbon atoms, a substitutedor unsubstituted aryl group having 6 to 40 carbon atoms, a trialkylsilylgroup wherein the alkyl group has 1 to 20 carbon atoms and may have asubstituent, an aryloxy group wherein the aryl group has 6 to 40 carbonatoms and may have a substituent, a halogen atom, or a cyano group,provided that at least two of R₂₄ to R₃₉ each represent a cyano group, atrifluoromethyl group or a fluorine atom and that those of R₂₄ to R₃₉which are adjacent to one another, may be linked together to form a ringstructure;

R₄₀ to R₅₇ each independently represent a hydrogen atom, a substitutedor unsubstituted alkyl group having 1 to 30 carbon atoms, a substitutedor unsubstituted alkoxy group having 1 to 30 carbon atoms, a substitutedor unsubstituted aryl group having 6 to 40 carbon atoms, a trialkylsilylgroup wherein the alkyl group has 1 to 20 carbon atoms and may have asubstituent, an aryloxy group wherein the aryl group has 6 to 40 carbonatoms and may have a substituent, a halogen atom, or a cyano group,provided that at least two of R₄₀ to R₅₇ each represent a cyano group, atrifluoromethyl group or a fluorine atom and that those of R₄₀ to R₅₇which are adjacent to one another, may be linked together to form a ringstructure; and

R₅₈-R₆₁ independently represents hydrogen, fluorine, or substituentsindependently selected from nitrile (—CN), nitro (—NO₂), sulfonyl(—SO₂R), sulfoxide (—SOR), trifluoromethyl (—CF₃), ester (—CO-DR), amide(—CONHR or —CO—NRR′), substituted or unsubstituted aryl, substituted orunsubstituted heteroaryl, or substituted or unsubstituted alkyl, where Rand R′ include substituted or unsubstituted alkyl or aryl; or R₅₈ andR₅₉, or R₆₀ and R₆₁, combine form a ring structure including an aromaticring, a heteroaromatic ring, or a non-aromatic ring, and each ring issubstituted or unsubstituted.

Preferably, the organic electron acceptor is:

Preferably, the organic electron donor is selected from the groupconsisting of:

More preferably, the organic electron acceptor is:

andthe organic electron donor is selected from the group consisting of:

Most preferably, the organic electron acceptor is Dopant 1 and theorganic electron donor is:

In one aspect, a second organic layer containing a non-polar solvent isdeposited over the first organic layer, and the first organic layer isinsoluble to the non-polar solvent in the second organic layer.Preferably, the first organic layer is a hole injection layer.Preferably, the second organic layer is a hole transporting layer, ahole blocking layer, an electron transporting layer, an electroninjection layer, or an emissive layer.

Non-polar solvents, as used herein, have a polarity index equal to orless than 3.5. In one aspect, the non-polar solvent is selected from thegroup consisting of benzene, carbon tetrachloride, cyclohexane,1,2-dichloroethane, dichloromethane, di-ethyl ether, heptane, hexane,methyl-t-butyl ether, pentane, di-iso-propyl ether, toluene, and xylene.Preferably, the non-polar solvent is toluene.

In one aspect, the solution process is spin coating or inkjet printing.

In another aspect, the organic electron acceptor and the organicelectron donor are mixed at a mole ratio of 1:1 or 2:1.

In yet another aspect, the insoluble organic layer forms when thecomposition is heated at a temperature no less than about 100° C. and nomore than about 250° C.

Additionally, a first device is provided, the device comprising anorganic light emitting device, which further comprises an anode; acathode; and a first organic layer disposed between the anode and thecathode, the organic layer comprising an electron acceptor and anelectron donor. Selections for the substituents, solvents, organicelectron acceptor and organic electron donor mole ratio, and temperaturedescribed as preferred for the method are also preferred for use in adevice that comprises an organic layer comprising the electron acceptorand the electron donor. These selections include those described atleast for A, B, C, R_(A), R_(B), R_(C), X, Y, R_(X), R_(Y), R₁-R₆₁,Y₁-Y₇, X₁, X₂, R′₁-R′₁₃, Ar₁-Ar₄, L₀, L₁, Z, r₁-r₄, and R₀₁-R₀₄.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows an organic light emitting device.

FIG. 2 shows an inverted organic light emitting device that does nothave a separate electron transport layer.

FIG. 3 shows a plot of device lifetimes.

DETAILED DESCRIPTION

Generally, an OLED comprises at least one organic layer disposed betweenand electrically connected to an anode and a cathode. When a current isapplied, the anode injects holes and the cathode injects electrons intothe organic layer(s). The injected holes and electrons each migratetoward the oppositely charged electrode. When an electron and holelocalize on the same molecule, an “exciton,” which is a localizedelectron-hole pair having an excited energy state, is formed. Light isemitted when the exciton relaxes via a photoemissive mechanism. In somecases, the exciton may be localized on an excimer or an exciplex.Non-radiative mechanisms, such as thermal relaxation, may also occur,but are generally considered undesirable.

The initial OLEDs used emissive molecules that emitted light from theirsinglet states (“fluorescence”) as disclosed, for example, in U.S. Pat.No. 4,769,292, which is incorporated by reference in its entirety.Fluorescent emission generally occurs in a time frame of less than 10nanoseconds.

More recently, OLEDs having emissive materials that emit light fromtriplet states (“phosphorescence”) have been demonstrated. Baldo et al.,“Highly Efficient Phosphorescent Emission from OrganicElectroluminescent Devices,” Nature, vol. 395, 151-154, 1998;(“Baldo-I”) and Baldo et al., “Very high-efficiency green organiclight-emitting devices based on electrophosphorescence,” Appl. Phys.Lett., vol. 75, No. 3, 4-6 (1999) (“Baldo-II”), which are incorporatedby reference in their entireties. Phosphorescence is described in moredetail in U.S. Pat. No. 7,279,704 at cols. 5-6, which are incorporatedby reference.

FIG. 1 shows an organic light emitting device 100. The figures are notnecessarily drawn to scale. Device 100 may include a substrate 110, ananode 115, a hole injection layer 120, a hole transport layer 125, anelectron blocking layer 130, an emissive layer 135, a hole blockinglayer 140, an electron transport layer 145, an electron injection layer150, a protective layer 155, and a cathode 160. Cathode 160 is acompound cathode having a first conductive layer 162 and a secondconductive layer 164. Device 100 may be fabricated by depositing thelayers described, in order. The properties and functions of thesevarious layers, as well as example materials, are described in moredetail in U.S. Pat. No. 7,279,704 at cols. 6-10, which are incorporatedby reference.

More examples for each of these layers are available. For example, aflexible and transparent substrate-anode combination is disclosed inU.S. Pat. No. 5,844,363, which is incorporated by reference in itsentirety. An example of a p-doped hole transport layer is m-MTDATA dopedwith F.sub.4-TCNQ at a molar ratio of 50:1, as disclosed in U.S. PatentApplication Publication No. 2003/0230980, which is incorporated byreference in its entirety. Examples of emissive and host materials aredisclosed in U.S. Pat. No. 6,303,238 to Thompson et al., which isincorporated by reference in its entirety. An example of an n-dopedelectron transport layer is BPhen doped with Li at a molar ratio of 1:1,as disclosed in U.S. Patent Application Publication No. 2003/0230980,which is incorporated by reference in its entirety. U.S. Pat. Nos.5,703,436 and 5,707,745, which are incorporated by reference in theirentireties, disclose examples of cathodes including compound cathodeshaving a thin layer of metal such as Mg:Ag with an overlyingtransparent, electrically-conductive, sputter-deposited ITO layer. Thetheory and use of blocking layers is described in more detail in U.S.Pat. No. 6,097,147 and U.S. Patent Application Publication No.2003/0230980, which are incorporated by reference in their entireties.Examples of injection layers are provided in U.S. Patent ApplicationPublication No. 2004/0174116, which is incorporated by reference in itsentirety. A description of protective layers may be found in U.S. PatentApplication Publication No. 2004/0174116, which is incorporated byreference in its entirety.

FIG. 2 shows an inverted OLED 200. The device includes a substrate 210,a cathode 215, an emissive layer 220, a hole transport layer 225, and ananode 230. Device 200 may be fabricated by depositing the layersdescribed, in order. Because the most common OLED configuration has acathode disposed over the anode, and device 200 has cathode 215 disposedunder anode 230, device 200 may be referred to as an “inverted” OLED.Materials similar to those described with respect to device 100 may beused in the corresponding layers of device 200. FIG. 2 provides oneexample of how some layers may be omitted from the structure of device100.

The simple layered structure illustrated in FIGS. 1 and 2 is provided byway of non-limiting example, and it is understood that embodiments ofthe invention may be used in connection with a wide variety of otherstructures. The specific materials and structures described areexemplary in nature, and other materials and structures may be used.Functional OLEDs may be achieved by combining the various layersdescribed in different ways, or layers may be omitted entirely, based ondesign, performance, and cost factors. Other layers not specificallydescribed may also be included. Materials other than those specificallydescribed may be used. Although many of the examples provided hereindescribe various layers as comprising a single material, it isunderstood that combinations of materials, such as a mixture of host anddopant, or more generally a mixture, may be used. Also, the layers mayhave various sublayers. The names given to the various layers herein arenot intended to be strictly limiting. For example, in device 200, holetransport layer 225 transports holes and injects holes into emissivelayer 220, and may be described as a hole transport layer or a holeinjection layer. In one embodiment, an OLED may be described as havingan “organic layer” disposed between a cathode and an anode. This organiclayer may comprise a single layer, or may further comprise multiplelayers of different organic materials as described, for example, withrespect to FIGS. 1 and 2.

Structures and materials not specifically described may also be used,such as OLEDs comprised of polymeric materials (PLEDs) such as disclosedin U.S. Pat. No. 5,247,190 to Friend et al., which is incorporated byreference in its entirety. By way of further example, OLEDs having asingle organic layer may be used. OLEDs may be stacked, for example asdescribed in U.S. Pat. No. 5,707,745 to Forrest et al, which isincorporated by reference in its entirety. The OLED structure maydeviate from the simple layered structure illustrated in FIGS. 1 and 2.For example, the substrate may include an angled reflective surface toimprove out-coupling, such as a mesa structure as described in U.S. Pat.No. 6,091,195 to Forrest et al., and/or a pit structure as described inU.S. Pat. No. 5,834,893 to Bulovic et al., which are incorporated byreference in their entireties.

Unless otherwise specified, any of the layers of the various embodimentsmay be deposited by any suitable method. For the organic layers,preferred methods include thermal evaporation, ink-jet, such asdescribed in U.S. Pat. Nos. 6,013,982 and 6,087,196, which areincorporated by reference in their entireties, organic vapor phasedeposition (OVPD), such as described in U.S. Pat. No. 6,337,102 toForrest et al., which is incorporated by reference in its entirety, anddeposition by organic vapor jet printing (OVJP), such as described inU.S. patent application Ser. No. 10/233,470, which is incorporated byreference in its entirety. Other suitable deposition methods includespin coating and other solution based processes. Solution basedprocesses are preferably carried out in nitrogen or an inert atmosphere.For the other layers, preferred methods include thermal evaporation.Preferred patterning methods include deposition through a mask, coldwelding such as described in U.S. Pat. Nos. 6,294,398 and 6,468,819,which are incorporated by reference in their entireties, and patterningassociated with some of the deposition methods such as ink jet and OVJD.Other methods may also be used. The materials to be deposited may bemodified to make them compatible with a particular deposition method.For example, substituents such as alkyl and aryl groups, branched orunbranched, and preferably containing at least 3 carbons, may be used insmall molecules to enhance their ability to undergo solution processing.Substituents having 20 carbons or more may be used, and 3-20 carbons isa preferred range. Materials with asymmetric structures may have bettersolution processibility than those having symmetric structures, becauseasymmetric materials may have a lower tendency to recrystallize.Dendrimer substituents may be used to enhance the ability of smallmolecules to undergo solution processing.

Devices fabricated in accordance with embodiments of the invention maybe incorporated into a wide variety of consumer products, including flatpanel displays, computer monitors, televisions, billboards, lights forinterior or exterior illumination and/or signaling, heads up displays,fully transparent displays, flexible displays, laser printers,telephones, cell phones, personal digital assistants (PDAs), laptopcomputers, digital cameras, camcorders, viewfinders, micro-displays,vehicles, a large area wall, theater or stadium screen, or a sign.Various control mechanisms may be used to control devices fabricated inaccordance with the present invention, including passive matrix andactive matrix. Many of the devices are intended for use in a temperaturerange comfortable to humans, such as 18 degrees C. to 30 degrees C., andmore preferably at room temperature (20-25 degrees C.).

The materials and structures described herein may have applications indevices other than OLEDs. For example, other optoelectronic devices suchas organic solar cells and organic photodetectors may employ thematerials and structures. More generally, organic devices, such asorganic transistors, may employ the materials and structures.

The terms halo, halogen, alkyl, cycloalkyl, alkenyl, alkynyl, arylkyl,heterocyclic group, aryl, aromatic group, and heteroaryl are known tothe art, and are defined in U.S. Pat. No. 7,279,704 at cols. 31-32,which are incorporated herein by reference.

A method of fabricating an organic light emitting device by solutiondepositing an organic layer comprising an organic electron donor and anorganic electron acceptor, which forms a layer insoluble to a non-polarsolvent, is provided. Preferably, the organic layer forms a holeinjection layer (HIL) in the device. The HIL is a particularly importantorganic layer in an OLED, because it helps provide holes to the emissivematerial in the emissive layer.

For solution processed OLEDs, an organic layer must be resistant to thesolvent used in the next organic layer. Previously, there were only twomethods available to provide an organic layer resistant to subsequentlayers. First, an orthogonal solvent may be used, such as PEDOT/PSS inaqueous solution. Second, cross-linkable polymers may be used. In thesecond instance, the film becomes insoluble after the layer is treatedto crosslink the polymers. (See, e.g., WO2008073440).

Here, a mixture of non-cross-linkable organic compounds forms a layerinsoluble to a non-polar solvent used in a subsequent organic layer. Asused herein, a “non-polar solvent” has a polarity index equal to or lessthan 3.5. The polarity index is defined in the Solvent Miscibility Tablein the Appendix of the Phenomenex catalog (also see,http://www.chemical-ecology.net/java/solvents.htm). The insolubleorganic layer includes an organic electron donor, e.g., a triarylaminederivative, and an organic electron acceptor, e.g., azatriphenylene.Especially preferred organic electron donors have an oxidation potentialless than 0.6 V vs Fc⁺/Fc. Organic electron acceptors have a firstreduction potential high than −1.0 V vs Fc⁺/Fc. Without being bound bytheory, it is believed that the organic electron donor and the organicelectron acceptor form an ionic charge transfer complex, therebycreating a layer insoluble to a non-polar solvent.

Vacuum thermal evaporation OLEDs containing triarylamine derivativeshave been reported in the literature. (See, e.g., US2008107919A1,US2008124572A1, and U.S. Pat. No. 6,344,283B1). In particular, the useof p-doped triarylamine derivatives as HIL materials for vacuum thermalevaporation OLEDs has been reported. (See Walzer et al., ChemicalReview, 2007, 107, 1233). Solution-processed OLEDs comprising aninsoluble layer of triarylamine in combination with an inorganicelectron donor, where the layer is embedded in metal oxide, have alsobeen reported. (See Suzuki et al., SID Digest, 2007, 1840-1843).However, an organic layer containing a non-cross-linkable triarylaminederivative in combination with an organic electron acceptor has not beenreported. The formation of a good organic layer film using thesecompounds was unexpected for several reasons. The properties of thecompounds suggest that they would make poor films for a solutionprocessed multilayer device. In particular, the crystallinity oftriarylamine derivatives and the azatriphenylene suggests poor filmformation. Further, these compounds have been traditionally used inOLEDs in which layers were deposited using VTE processing, a method verydifferent from solution-processing.

Moreover, formation of an insoluble layer upon heating the triarylaminederivative and conductivity dopant composition was surprising. It wouldbe expected that the film would have very poor solvent resistance, thusunsuitable for use in a solution processed multilayer device. If heatedseparately, the compounds would not become insoluble. Here, heating theorganic layer comprising the organic electron donor, i.e., triarylaminederivative, and the organic electron acceptor, i.e., azatriphenylene,unexpectedly resulted in formation of a layer insoluble to a non-polarsolvent. There are no prior reports of an insoluble organic layercomprising small molecule compounds that do not require cross-linking.Thus, there was no expectation that these small molecule materials wouldbecome insoluble when heated. The insoluble layer described herein isespecially beneficial for fabrication of solution processed OLEDs.

Further, devices comprising an organic layer containing the organicelectron donor, i.e., triarylamine derivative, and the organic electronacceptor, i.e., azatriphenylene, may have improved properties, includinglonger lifetime, good reproducibility, lower operating voltage whilemaintaining luminous efficiency, and improved purification, asillustrated in FIG. 3.

A method of fabricating an organic light emitting device is provided.The method comprises providing an electrode, depositing a first organiclayer in contact with the electrode by a solution process, and heatingthe first organic layer to form a layer that is insoluble in a non-polarsolvent. Preferably, the electrode is an anode, and the first organiclayer is deposited in contact with the anode.

The first organic layer comprises an organic electron acceptor and anorganic electron donor having the formula:

A, B, and C are 5 or 6 membered cyclic or heterocyclic rings. R_(A),R_(B), and R_(C) are independent selected from the group consisting ofhydrogen, halogen, alkyl, alkoxy, amino, alkenyl, alkynyl, aryl andheteroaryl. R_(A), R_(B), and R_(C) are optionally fused to A, B, and C.At least two of R_(A), R_(B), and R_(C) contain the structure:

X and Y are independently 5 or 6 membered cyclic or heterocyclic rings.R_(X) and R_(Y) are independently selected from the group consisting ofhydrogen, halogen, alkyl, alkoxy, amino, alkenyl, alkynyl, aryl andheteroaryl. R_(X) and R_(Y) are optionally fused to X and Y. R_(X) andR_(Y) are optionally connected to A and B.

In one aspect, the organic electron donor has the formula:

L₁ represents a substituted or unsubstituted arylene group having 6 to60 carbon atoms forming the aromatic ring, a substituted orunsubstituted fluorenylene group, or a substituted or unsubstitutedheteroarylene group having 5 to 60 atoms forming a ring; Ar₁ and Ar₂each independently represents a substituted or unsubstituted aryl grouphaving 6 to 60 carbon atoms forming the aromatic ring or a substitutedor unsubstituted heteroaryl group having 5 to 60 atoms forming a ring;R′₁ represents a substituted or unsubstituted aryl group having 6 to 60carbon atoms forming the aromatic ring; R′Z₂ represents a hydrogen atom,a substituted or unsubstituted aryl group having 6 to 60 carbon atomsforming the aromatic ring, a substituted or unsubstituted alkyl grouphaving 1 to 50 carbon atoms, a substituted or unsubstituted alkoxy grouphaving 1 to 50 carbon atoms, a substituted or unsubstituted aryloxygroup having 6 to 50 atoms forming a ring, a substituted orunsubstituted arylthio group having 5 to 50 atoms forming a ring, asubstituted or unsubstituted alkoxycarbonyl group having 2 to 50 carbonatoms, an amino group substituted by a substituted or unsubstituted arylgroup having 6 to 50 carbon atoms forming the aromatic ring, a halogenatom, a cyano group, a nitro group, a hydroxyl group or a carboxylgroup; with the proviso that neither Ar₁ nor Ar₂ contains a fluorenestructure, and that the number of a carbazole structures in the aromaticamine derivative represented by the formula is 1 or 2.

In another aspect, the organic electron donor has the formula:

Z is selected from the group consisting of a substituted orunsubstituted C1-C30 alkylene group, a substituted or unsubstitutedC2-C30 alkenylene group, a substituted or unsubstituted C6-C30 arylenegroup, a substituted or unsubstituted C2-C30 heteroarylene group, and asubstituted or unsubstituted C2-C30 heterocyclic group; each of R′₃,R′₄, R′₅, R′₆, R′₇, and R′₈ is independently selected from the groupconsisting of a hydrogen atom, a substituted or unsubstituted C1-C30alkyl group, a substituted or unsubstituted C1-C30 alkoxy group, asubstituted or unsubstituted C6-C30 aryl group, a substituted orunsubstituted C6-C30 aryloxy group, a substituted or unsubstitutedC2-C30 heterocyclic group, a substituted or unsubstituted C6-C30condensed polycyclic group, a hydroxy group, a cyano group, and asubstituted or unsubstituted amino group, and, alternatively, two ormore adjacent groups among R′₃, R′₄, R′₅, R′₆, R′₇, and R′₈ can beconnected to each other to form a saturated or unsaturated carbocycle;and wherein each of Ar₃ and Ar₄ are independently a substituted orunsubstituted C6-C30 aryl group or a substituted or unsubstituted C2-C30heteroaryl group.

In yet another aspect, the organic electron donor has the formula:

L₀ is any one of o-, p-, and m-phenylene groups which have two, three orfour rings and which have a substituent with the proviso that when L₀ isa phenylene group having four rings, the phenylene group may have anunsubstituted or substituted aminophenyl group somewhere therein, andR₀₁, R₀₂, R₀₃ and R₀₄ are any one of the following groups:

R′₉, R′₁₀, R′₁₁, R′₁₂ and R′₁₃ are each a substituted or unsubstitutedaryl group, and r₁, r₂, r₃ and r₄ are each an integer of 0 to 5 with theproviso that r₁+r₂+r₃+r₄≧1.

In one aspect, the organic electron acceptor is selected from the groupconsisting of:

R₁, R₂, R₃, R₄, R₅, and R₆ are independently chosen from the groupconsisting of hydrogen, halogen, nitrile, nitro, sulfonyl, solfoxide,sulfonamide, sulfonate, trifluoromethyl, ester, amide, straight-chain orbranched C1-C12 alkoxy, straight-chain or branched C1-C12 alkyl,aromatic or non-aromatic (substituted or unsubstituted) heterocyclic,substituted or unsubstituted aryl, mono- or di-(substituted orunsibstituted)aryl-amine, and (substituted orunsubstituted)alkyl-(substituted or unsubstituted)aryl-amine; or whereR₁ and R₂, R₃ and R₄, and R₅ and R₆ combine form a ring structureincluding an aromatic ring, a heteroaromatic ring, or a non-aromaticring, and each ring is substituted or unsubstituted;

Y₁ to Y₄ are independently a carbon atom or a nitrogen atom. R₇ to R₁₀are independently a hydrogen atom, an alkyl group, a substituted orunsubstituted aryl group, a substituted or unsubstituted heterocycle, ahalogen atom, a fluoroalkyl group or a cyano group. R₇ and R₈, and R₉and R₁₀ are independently bonded to form a substituted or unsubstitutedaromatic ring or a substituted or unsubstituted heterocycle. X₁ isselected from the group consisting of:

Y₅ to Y₇ are independently a hydrogen atom, a fluoroalkyl group, analkyl group, an aryl group or a heterocyclic group; and Y₆ and Y₇ mayform a ring;

X₂ is

C(R₂₃) or N, R₁₁ to R₂₃ each independently represent a hydrogen atom, asubstituted or unsubstituted alkyl group having 1 to 30 carbon atoms, asubstituted or unsubstituted alkoxy group having 1 to 30 carbon atoms, asubstituted or unsubstituted aryl group having 6 to 40 carbon atoms, atrialkylsilyl group wherein the alkyl group has 1 to 20 carbon atoms andmay have a substituent, an aryloxy group wherein the aryl group has 6 to40 carbon atoms and may have a substituent, a halogen atom, or a cyanogroup, provided that at least two of R₁₁ to R₂₃ each represent a cyanogroup, a trifluoromethyl group or a fluorine atom and that those of R₁₁to R₂₃, which are adjacent to one another, may be linked together toform a ring structure;

R₂₄ to R₃₉ each independently represent a hydrogen atom, a substitutedor unsubstituted alkyl group having 1 to 30 carbon atoms, a substitutedor unsubstituted alkoxy group having 1 to 30 carbon atoms, a substitutedor unsubstituted aryl group having 6 to 40 carbon atoms, a trialkylsilylgroup wherein the alkyl group has 1 to 20 carbon atoms and may have asubstituent, an aryloxy group wherein the aryl group has 6 to 40 carbonatoms and may have a substituent, a halogen atom, or a cyano group,provided that at least two of R₂₄ to R₃₉ each represent a cyano group, atrifluoromethyl group or a fluorine atom and that those of R₂₄ to R₃₉which are adjacent to one another, may be linked together to form a ringstructure;

R₄₀ to R₅₇ each independently represent a hydrogen atom, a substitutedor unsubstituted alkyl group having 1 to 30 carbon atoms, a substitutedor unsubstituted alkoxy group having 1 to 30 carbon atoms, a substitutedor unsubstituted aryl group having 6 to 40 carbon atoms, a trialkylsilylgroup wherein the alkyl group has 1 to 20 carbon atoms and may have asubstituent, an aryloxy group wherein the aryl group has 6 to 40 carbonatoms and may have a substituent, a halogen atom, or a cyano group,provided that at least two of R₄₀ to R₅₇ each represent a cyano group, atrifluoromethyl group or a fluorine atom and that those of R₄₀ to R₅₇which are adjacent to one another, may be linked together to form a ringstructure; and

R₅₈-R⁶¹ independently represents hydrogen, fluorine, or substituentsindependently selected from nitrile (—CN), nitro (—NO₂), sulfonyl(—SO₂R), sulfoxide (—SOR), trifluoromethyl (—CF₃), ester (—CO-DR), amide(—CONHR or —CO—NRR′), substituted or unsubstituted aryl, substituted orunsubstituted heteroaryl, or substituted or unsubstituted alkyl, where Rand R′ include substituted or unsubstituted alkyl or aryl; or R₅₈ andR₅₉, or R₆₀ and R₆₁, combine form a ring structure including an aromaticring, a heteroaromatic ring, or a non-aromatic ring, and each ring issubstituted or unsubstituted.

Preferably, the organic electron acceptor is:

Preferably, the organic electron donor is selected from the groupconsisting of:

More preferably, the organic electron acceptor is:

andthe organic electron donor is selected from the group consisting of:

Most preferably, the organic electron acceptor is Dopant 1 and theorganic electron donor is:

In one aspect, a second organic layer containing a non-polar solvent isdeposited over the first organic layer, and the first organic layer isinsoluble to the non-polar solvent in the second organic layer.Preferably, the first organic layer is a hole injection layer.Preferably, the second organic layer is a hole transporting layer, ahole blocking layer, an electron transporting layer, an electroninjection layer, or an emissive layer.

Non-polar solvents, as used herein, have a polarity index equal to orless than 3.5. Examples of non-polar solvents include, withoutlimitation, benzene, carbon tetrachloride, cyclohexane,1,2-dichloroethane, dichloromethane, di-ethyl ether, heptane, hexane,methyl-t-butyl ether, pentane, di-iso-propyl ether, toluene, and xylene.Preferably, the non-polar solvent is toluene.

In one aspect, the solution process is spin coating or inkjet printing.

In another aspect, the organic electron acceptor and the organicelectron donor are mixed at a mole ratio of 1:1 or 2:1. Without beingbound by theory, it is believed that the high mole ratio of the organicelectron acceptor provides for good formation of the ionic complexbetween the organic electron acceptor and the organic electron donor. Indoped VTE HILs, only a few percent of electron acceptor, normally lessthan 5%, is required to achieve efficient electron injection from theanode and high conductivity. It might not be enough, however, to form aninsoluble layer with low electron acceptor percentage. For example, whenthe mole ratio of donor to acceptor is 1:20, the majority of theelectron donor does not react with the electron acceptor. Therefore, amuch higher electron acceptor concentration (mole ratio) may be needed.

In yet another aspect, the insoluble organic layer forms when thecomposition is heated at a temperature no less than about 100° C. and nomore than about 250° C. It is believed that the ionic complex formedbetween the organic electron acceptor and the organic electron donorforms more efficiently, solvent is better evaporated and materials donot breakdown within this temperature range.

Additionally, a first device is provided, the device comprising anorganic light emitting device, which further comprises an anode; acathode; and a first organic layer disposed between the anode and thecathode. The first organic layer comprises an organic electron acceptorand an organic electron donor having the formula:

A, B, and C are 5 or 6 membered cyclic or heterocyclic rings. R_(A),R_(B), and R_(C) are independently selected from the group consisting ofhydrogen, halogen, alkyl, alkoxy, amino, alkenyl, alkynyl, aryl andheteroaryl. R_(A), R_(B), and R_(C) are optionally fused to A, B, and C.At least two of R_(A), R_(B), and R_(C) contain the structure:

X and Y are independently 5 or 6 membered cyclic or heterocyclic rings.R_(X) and Ry are independent selected from the group consisting ofhydrogen, halogen, alkyl, alkoxy, amino, alkenyl, alkynyl, aryl andheteroaryl. R_(X) and R_(Y) are optionally fused to X and Y. R_(X) andR_(Y) are optionally connected to A and B. When the organic electronacceptor and the organic electron donor are heated, they form a layerthat is insoluble in a non-polar solvent.

In one aspect, the first organic layer is deposited in contact with theanode.

In one aspect, the organic electron donor has the formula:

L₁ represents a substituted or unsubstituted arylene group having 6 to60 carbon atoms forming the aromatic ring, a substituted orunsubstituted fluorenylene group, or a substituted or unsubstitutedheteroarylene group having 5 to 60 atoms forming a ring; Ar₁ and Ar₂each independently represents a substituted or unsubstituted aryl grouphaving 6 to 60 carbon atoms forming the aromatic ring or a substitutedor unsubstituted heteroaryl group having 5 to 60 atoms forming a ring;R′₁ represents a substituted or unsubstituted aryl group having 6 to 60carbon atoms forming the aromatic ring; R′₂ represents a hydrogen atom,a substituted or unsubstituted aryl group having 6 to 60 carbon atomsforming the aromatic ring, a substituted or unsubstituted alkyl grouphaving 1 to 50 carbon atoms, a substituted or unsubstituted alkoxy grouphaving 1 to 50 carbon atoms, a substituted or unsubstituted aryloxygroup having 6 to 50 atoms forming a ring, a substituted orunsubstituted arylthio group having 5 to 50 atoms forming a ring, asubstituted or unsubstituted alkoxycarbonyl group having 2 to 50 carbonatoms, an amino group substituted by a substituted or unsubstituted arylgroup having 6 to 50 carbon atoms forming the aromatic ring, a halogenatom, a cyano group, a nitro group, a hydroxyl group or a carboxylgroup; with the proviso that neither Ar₁ nor Ar₂ contains a fluorenestructure, and that the number of a carbazole structures in the aromaticamine derivative represented by the formula is 1 or 2.

In another aspect, the organic electron donor has the formula:

Z is selected from the group consisting of a substituted orunsubstituted C1-C30 alkylene group, a substituted or unsubstitutedC2-C30 alkenylene group, a substituted or unsubstituted C6-C30 arylenegroup, a substituted or unsubstituted C2-C30 heteroarylene group, and asubstituted or unsubstituted C2-C30 heterocyclic group; each of R′₃,R′₄, R′₅, R′₆, R′₇, and R′8 is independently selected from the groupconsisting of a hydrogen atom, a substituted or unsubstituted C1-C30alkyl group, a substituted or unsubstituted C1-C30 alkoxy group, asubstituted or unsubstituted C6-C30 aryl group, a substituted orunsubstituted C6-C30 aryloxy group, a substituted or unsubstitutedC2-C30 heterocyclic group, a substituted or unsubstituted C6-C30condensed polycyclic group, a hydroxy group, a cyano group, and asubstituted or unsubstituted amino group, and, alternatively, two ormore adjacent groups among R′₃, R′₄, R′₅, R′₆, R′₇, and R′₈ can beconnected to each other to form a saturated or unsaturated carbocycle;and wherein each of Ar₃ and Ar₄ are independently a substituted orunsubstituted C6-C30 aryl group or a substituted or unsubstituted C2-C30heteroaryl group.

In yet another aspect, the organic electron donor has the formula:

L₀ is any one of o-, p-, and m-phenylene groups which have two, three orfour rings and which have a substituent with the proviso that when L₀ isa phenylene group having four rings, the phenylene group may have anunsubstituted or substituted aminophenyl group somewhere therein, andR₀₁, R₀₂, R₀₃ and R₀₄ are any one of the following groups:

R′₉, R′₁₀, R′₁₁, R′₁₂ and R′₁₃ are each a substituted or unsubstitutedaryl group, and r₁, r₂, r₃ and r₄ are each an integer of 0 to 5 with theproviso that r₁+r₂+r₃+r₄≧1.

In one aspect, the organic electron acceptor is selected from the groupconsisting of:

R₁, R₂, R₃, R₄, R₅, and R₆ are independently chosen from the groupconsisting of hydrogen, halogen, nitrile, nitro, sulfonyl, solfoxide,sulfonamide, sulfonate, trifluoromethyl, ester, amide, straight-chain orbranched C1-C12 alkoxy, straight-chain or branched C1-C12 alkyl,aromatic or non-aromatic (substituted or unsubstituted) heterocyclic,substituted or unsubstituted aryl, mono- or di-(substituted orunsubstituted)aryl-amine, and (substituted orunsubstituted)alkyl-(substituted or unsubstituted)aryl-amine; or whereR₁ and R₂, R₃ and R₄, and R₅ and R₆ combine form a ring structureincluding an aromatic ring, a heteroaromatic ring, or a non-aromaticring, and each ring is substituted or unsubstituted;

Y₁ to Y₄ are independently a carbon atom or a nitrogen atom. R₇ to R₁₀are independently a hydrogen atom, an alkyl group, a substituted orunsubstituted aryl group, a substituted or unsubstituted heterocycle, ahalogen atom, a fluoroalkyl group or a cyano group. R₇ and R₈, and R₉and R₁₀ are independently bonded to form a substituted or unsubstitutedaromatic ring or a substituted or unsubstituted heterocycle. X₁ isselected from the group consisting of:

Y₅ to Y₇ are independently a hydrogen atom, a fluoroalkyl group, analkyl group, an aryl group or a heterocyclic group; and Y₆ and Y₇ mayform a ring;

X₂ is

C(R₂₃) or N, R₁₁ to R₂₃ each independently represent a hydrogen atom, asubstituted or unsubstituted alkyl group having 1 to 30 carbon atoms, asubstituted or unsubstituted alkoxy group having 1 to 30 carbon atoms, asubstituted or unsubstituted aryl group having 6 to 40 carbon atoms, atrialkylsilyl group wherein the alkyl group has 1 to 20 carbon atoms andmay have a substituent, an aryloxy group wherein the aryl group has 6 to40 carbon atoms and may have a substituent, a halogen atom, or a cyanogroup, provided that at least two of R₁₁ to R₂₃ each represent a cyanogroup, a trifluoromethyl group or a fluorine atom and that those of R₁₁to R₂₃, which are adjacent to one another, may be linked together toform a ring structure;

R₂₄ to R₃₉ each independently represent a hydrogen atom, a substitutedor unsubstituted alkyl group having 1 to 30 carbon atoms, a substitutedor unsubstituted alkoxy group having 1 to 30 carbon atoms, a substitutedor unsubstituted aryl group having 6 to 40 carbon atoms, a trialkylsilylgroup wherein the alkyl group has 1 to 20 carbon atoms and may have asubstituent, an aryloxy group wherein the aryl group has 6 to 40 carbonatoms and may have a substituent, a halogen atom, or a cyano group,provided that at least two of R₂₄ to R₃₉ each represent a cyano group, atrifluoromethyl group or a fluorine atom and that those of R₂₄ to R₃₉which are adjacent to one another, may be linked together to form a ringstructure;

R₄₀ to R₅₇ each independently represent a hydrogen atom, a substitutedor unsubstituted alkyl group having 1 to 30 carbon atoms, a substitutedor unsubstituted alkoxy group having 1 to 30 carbon atoms, a substitutedor unsubstituted aryl group having 6 to 40 carbon atoms, a trialkylsilylgroup wherein the alkyl group has 1 to 20 carbon atoms and may have asubstituent, an aryloxy group wherein the aryl group has 6 to 40 carbonatoms and may have a substituent, a halogen atom, or a cyano group,provided that at least two of R₄₀ to R₅₇ each represent a cyano group, atrifluoromethyl group or a fluorine atom and that those of R₄₀ to R₅₇which are adjacent to one another, may be linked together to form a ringstructure; and

R₅₈-R₆₁ independently represents hydrogen, fluorine, or substituentsindependently selected from nitrile (—CN), nitro (—NO₂), sulfonyl(—SO₂R), sulfoxide (—SOR), trifluoromethyl (—CF₃), ester (—CO-DR), amide(—CONHR or —CO—NRR′), substituted or unsubstituted aryl, substituted orunsubstituted heteroaryl, or substituted or unsubstituted alkyl, where Rand R′ include substituted or unsubstituted alkyl or aryl; or R₅₈ andR₅₉, or R₆₀ and R₆₁, combine form a ring structure including an aromaticring, a heteroaromatic ring, or a non-aromatic ring, and each ring issubstituted or unsubstituted.

Preferably, the organic electron acceptor has the formula:

Preferably, the organic electron donor is selected from the groupconsisting of:

More preferably, the organic electron acceptor is Dopant 1 and theorganic electron donor is selected from the group consisting of:

Most preferably, the organic electron donor has the formula:

In one aspect, the organic electron acceptor and the organic electrondonor form a layer that is insoluble in a non-polar solvent having apolarity index equal to or less than 3.5. Examples of non-polar solventsinclude, without limitation, benzene, carbon tetrachloride, cyclohexane,1,2-dichloroethane, dichloromethane, di-ethyl ether, heptane, hexane,methyl-t-butyl ether, pentane, di-iso-propyl ether, toluene, and xylene.Preferably, the non-polar solvent is toluene.

In one aspect, the first device is a consumer product. In anotheraspect, the first device is an organic light emitting device.

In another aspect, the layer that is insoluble in a non-polar solventforms when the organic electron acceptor and the organic electron donorare heated at a temperature no less than about 100° C. and no more thanabout 250° C. For reasons discussed above, it is believed that the ionicomplex between the organic electron acceptor and the organic electrondonor forms more efficiently within this temperature range.

In one aspect, the organic electron acceptor and the organic electrondonor are mixed at a mole ratio of 1:1 or 2:1.

In another aspect, a second organic layer containing a non-polar solventis deposited over the first organic layer, and the first organic layeris insoluble to the non-polar solvent contained in the second organiclayer. Preferably, the first organic layer is a hole injection layer. Inyet a further aspect, the second organic layer is a hole transportinglayer, a hole blocking layer, an electron transporting layer, anelectron injection layer, or an emissive layer.

The materials described herein as useful for a particular layer in anorganic light emitting device may be used in combination with a widevariety of other materials present in the device. For example, emissivedopants disclosed herein may be used in conjunction with a wide varietyof hosts, transport layers, blocking layers, injection layers,electrodes and other layers that may be present. The materials describedor referred to below are non-limiting examples of materials that may beuseful in combination with the compounds disclosed herein, and one ofskill in the art can readily consult the literature to identify othermaterials that may be useful in combination.

In addition to and/or in combination with the materials disclosedherein, many hole injection materials, hole transporting materials, hostmaterials, dopant materials, exiton/hole blocking layer materials,electron transporting and electron injecting materials may be used in anOLED. Non-limiting examples of the materials that may be used in an OLEDin combination with materials disclosed herein are listed in Table 1below. Table 1 lists non-limiting classes of materials, non-limitingexamples of compounds for each class, and references that disclose thematerials.

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EXPERIMENTAL

Several devices were fabricated as follows:

The hole injection layer (HIL) solutions were prepared by mixing thetriarylamine derivative and conductivity dopant (mole ratio 1:1 or 2:1)in an organic solvent. Table 2 shows the composition of the HILsolutions. The HIL film was formed by spin coating the HIL solution atvarious speeds. The film was then baked at 250° C.

TABLE 2 Organic Organic Total electron electron Mole concentrationacceptor donor ratio Solvent (mg/mL) HIL1 Compound 1 Dopant 1 1:1Cyclohexanone 15 HIL2 Compound 2 Dopant 1 1:1 Cyclohexanone 15 HIL3Compound 2 Dopant 1 2:1 Cyclohexanone 13

Green-emitting OLEDs were made using HIL1, HIL2, and HIL3 for the holeinjection layer. To form the HIL, the solution was spin-coated at 2500rpm for 60 seconds onto a patterned indium tin oxide (ITO) electrode.The resulting film was baked for 30 minutes at 250° C.

As used herein, the following compounds have the following structures:

As used herein, Dopant 1 is a mixture of A, B, C, and D in a ratio of1.9:18.0:46.7:32.8, wherein A, B, C, and D have the followingstructures:

To check the insolubility, the HIL1 solution was spun-coated on the topof a Si-wafer, and the spin and baking conditions were same as on ITO.After baking, the HIL1 film was measured. Then, neat toluene solvent wasspun on the top of HIL1 film to try wash-off the HIL1 film, which is thesame as the hole transporting layer (HTL) spin-coating process used indevice fabrication. The HIL1 film thickness was measured with 133 Åbefore washing, and 86 Å after toluene washing. About 60% of the filmthickness was left after toluene washing.

A comparative green-emitting device was fabricated using PEDOT:PSS(Baytron, CH8000) as the HIL material. The PEDOT:PSS in an aqueousdispersion was spin-coated at 4000 rpm for 60 seconds onto a patternedindium tin oxide (ITO) electrode. The resulting film was baked for 5minutes at 200° C.

On top of the HIL, a hole transporting layer (HTL) and then emissivelayer (EML) were also formed by spin-coating. The HTL was made byspin-coating a 0.5 wt % solution of the hole transporting material HTL-1in toluene at 4000 rpm for 60 seconds. The HTL film was baked at 200° C.for 30 minutes. After baking, the HTL became an insoluble film.

The EML was made using Host-1 as the host material and thegreen-emitting phosphorescent Dopant-1 as the emissive material. To formthe EML, a toluene solution containing Host-1 and Dopant-1 (of total0.75 wt %), with a Host-1:Dopant-1 weight ratio of 88:12, wasspin-coated onto the insoluble HTL at 1000 rpm for 60 seconds, and thenbaked at 100° C. for 30 minutes.

The hole blocking layer (containing the compound HPT), the electrontransport layer (containing Alq₃), the electron injection layer(containing LiF), and the aluminum electrode were sequentially vacuumdeposited.

For performance testing, these green-emitting devices were operatedunder a constant DC current. FIG. 3 shows a plot of luminance intensityversus time for the devices. The lifetime LT₈₀ (as measured by the timeelapsed for decay of brightness to 80% of the initial level) were 9 h,143 h, 87 h, and 131 h for the Comparative, HIL1, HIL2, and HIL3devices, respectively. The devices with new HIL materials have muchlonger lifetime than the comparative PEDOT:PSS device.

Table 3 summarizes the performance of the green-emitting devices. Asseen in Table 3, the HIL1 device had similar performance in luminousefficiency (39 cd/A) and lower operating voltage (7.8 V) compared toComparative device (42 cd/A, 8.1 V) at 4000 cd/m². However, HIL2 andHIL3 had lower efficiency and higher voltage than the Comparativedevice.

TABLE 3 Comparative HIL1 HIL2 HIL3 Device Device Device Device OperatingVoltage (V) 8.1 7.8 8.2 8.6 @ 4000 cd/m² Luminous Efficiency 42 39 20 20(cd/A) @ 4000 cd/m² Lifetime LT₈₀ (hours) 9 143 87 131 from 4000 cd/m²Color Coordinate (0.36, (0.33, (0.33, (0.32, CIE 1931 (x, y) 0.60) 0.62)0.63) 0.63)

It is understood that the various embodiments described herein are byway of example only, and are not intended to limit the scope of theinvention. For example, many of the materials and structures describedherein may be substituted with other materials and structures withoutdeviating from the spirit of the invention. The present invention asclaimed may therefore includes variations from the particular examplesand preferred embodiments described herein, as will be apparent to oneof skill in the art. It is understood that various theories as to whythe invention works are not intended to be limiting.

The invention claimed is:
 1. A method of fabricating an organic lightemitting device, the method comprising: providing an electrode;depositing a first organic layer in contact with the electrode by asolution process, wherein the first organic layer comprises an organicelectron acceptor; and an organic electron donor having the formula:

wherein A, B, and C are 5 or 6 membered cyclic or heterocyclic rings;wherein R_(A), R_(B), and R_(C) are independent selected from the groupconsisting of hydrogen, halogen, alkyl, alkoxy, amino, alkenyl, alkynyl,aryl and heteroaryl; and wherein R_(A), R_(B), and R_(C) are optionallyfused to A, B, and C; and wherein at least two of R_(A), R_(B), andR_(C) contain the structure:

wherein X and Y are independently 5 or 6 membered cyclic or heterocyclicrings; wherein R_(X) and R_(Y) are independent selected from the groupconsisting of hydrogen, halogen, alkyl, alkoxy, amino, alkenyl, alkynyl,aryl and heteroaryl; wherein R_(X) and R_(Y) are optionally fused to Xand Y; wherein R_(X) and R_(Y) are optionally connected to A and B; andheating the first organic layer to form a layer that is insoluble in anon-polar solvent.
 2. The method of claim 1, wherein the non-polarsolvent is selected from the group consisting of benzene, carbontetrachloride, cyclohexane, 1,2-dichloroethane, dichloromethane,di-ethyl ether, heptane, hexane, methyl-t-butyl ether, pentane,di-iso-propyl ether, toluene, and xylene.
 3. The method of claim 1,wherein the non-polar solvent is toluene.
 4. The method of claim 1,wherein the organic electron donor has the formula:

wherein L₁ represents a substituted or unsubstituted arylene grouphaving 6 to 60 carbon atoms forming the aromatic ring, a substituted orunsubstituted fluorenylene group, or a substituted or unsubstitutedheteroarylene group having 5 to 60 atoms forming a ring; Ar₁ and Ar₂each independently represents a substituted or unsubstituted aryl grouphaving 6 to 60 carbon atoms forming the aromatic ring or a substitutedor unsubstituted heteroaryl group having 5 to 60 atoms forming a ring;R′₁ represents a substituted or unsubstituted aryl group having 6 to 60carbon atoms forming the aromatic ring; R′₂ represents a hydrogen atom,a substituted or unsubstituted aryl group having 6 to 60 carbon atomsforming the aromatic ring, a substituted or unsubstituted alkyl grouphaving 1 to 50 carbon atoms, a substituted or unsubstituted alkoxy grouphaving 1 to 50 carbon atoms, a substituted or unsubstituted aryloxygroup having 6 to 50 atoms forming a ring, a substituted orunsubstituted arylthio group having 5 to 50 atoms forming a ring, asubstituted or unsubstituted alkoxycarbonyl group having 2 to 50 carbonatoms, an amino group substituted by a substituted or unsubstituted arylgroup having 6 to 50 carbon atoms forming the aromatic ring, a halogenatom, a cyano group, a nitro group, a hydroxyl group or a carboxylgroup; with the proviso that neither Ar₁ nor Ar₂ contains a fluorenestructure, and that the number of a carbazole structures in the aromaticamine derivative represented by the formula is 1 or
 2. 5. The method ofclaim 1, wherein the organic electron donor has the formula:

wherein Z is selected from the group consisting of a substituted orunsubstituted C1-C30 alkylene group, a substituted or unsubstitutedC2-C30 alkenylene group, a substituted or unsubstituted C6-C30 arylenegroup, a substituted or unsubstituted C2-C30 heteroarylene group, and asubstituted or unsubstituted C2-C30 heterocyclic group; each of R′₃,R′₄, R′₅, R′₆, R′₇, and R′₈ is independently selected from the groupconsisting of a hydrogen atom, a substituted or unsubstituted C1-C30alkyl group, a substituted or unsubstituted C1-C30 alkoxy group, asubstituted or unsubstituted C6-C30 aryl group, a substituted orunsubstituted C6-C30 aryloxy group, a substituted or unsubstitutedC2-C30 heterocyclic group, a substituted or unsubstituted C6-C30condensed polycyclic group, a hydroxy group, a cyano group, and asubstituted or unsubstituted amino group, and, alternatively, two ormore adjacent groups among R′₃, R′₄, R′₅, R′₆, R′₇, and R′₈ can beconnected to each other to form a saturated or unsaturated carbocycle;and wherein each of Ar₃ and Ar₄ are independently a substituted orunsubstituted C6-C30 aryl group or a substituted or unsubstituted C2-C30heteroaryl group.
 6. The method of claim 1, wherein the organic electrondonor has the formula:

wherein L₀ is any one of o-, p-, and m-phenylene groups which have two,three or four rings and which have a substituent with the proviso thatwhen L₀ is a phenylene group having four rings, the phenylene group mayhave an unsubstituted or substituted aminophenyl group somewheretherein, and R₀₁, R₀₂, R₀₃ and R₀₄ are any one of the following groups:

wherein R′₉, R′₁₀, R′₁₁, R′₁₂ and R′₁₃ are each a substituted orunsubstituted aryl group, and r₁, r₂, r₃ and r₄ are each an integer of 0to 5 with the proviso that r₁+r₂+r₃+r₄≧1.
 7. The method of claim 1,wherein the electrode is an anode, and the first organic layer isdeposited in contact with the anode.
 8. The method of claim 1, wherein asecond organic layer containing a non-polar solvent is deposited overthe first organic layer, and the first organic layer is insoluble to thenon-polar solvent in the second organic layer.
 9. The method of claim 1,wherein the first organic layer is a hole injection layer.
 10. Themethod of claim 1, wherein the second organic layer is a holetransporting layer, a hole blocking layer, an electron transportinglayer, an electron injection layer, or an emissive layer.
 11. The methodof claim 1, wherein the organic electron acceptor is selected from thegroup of compounds having the formulas:

wherein R₁, R₂, R₃, R₄, R₅, and R₆ are independently chosen from thegroup consisting of hydrogen, halogen, nitrile, nitro, sulfonyl,solfoxide, sulfonamide, sulfonate, trifluoromethyl, ester, amide,straight-chain or branched C1-C12 alkoxy, straight-chain or branchedC1-C12 alkyl, aromatic or non-aromatic (substituted or unsubstituted)heterocyclic, substituted or unsubstituted aryl, mono- ordi-(substituted or unsubstituted)aryl-amine, and (substituted orunsubstituted)alkyl-(substituted or unsubstituted)aryl-amine; or whereR₁ and R₂, R₃ and R₄, and R₅ and R₆ combine form a ring structureincluding an aromatic ring, a heteroaromatic ring, or a non-aromaticring, and each ring is substituted or unsubstituted;

wherein Y₁ to Y₄ are independently a carbon atom or a nitrogen atom; R₇to R₁₀ are independently a hydrogen atom, an alkyl group, a substitutedor unsubstituted aryl group, a substituted or unsubstituted heterocycle,a halogen atom, a fluoroalkyl group or a cyano group; R₇ and R₈, and R₉and R₁₀ are independently bonded to form a substituted or unsubstitutedaromatic ring or a substituted or unsubstituted heterocycle; X₁ isselected from the group consisting of:

wherein Y₅ to Y₇ are independently a hydrogen atom, a fluoroalkyl group,an alkyl group, an aryl group or a heterocyclic group; and Y₆ and Y₇ mayform a ring;

wherein X₂ is

wherein C(R₂₃) or N, R₁₁ to R₂₃ each independently represent a hydrogenatom, a substituted or unsubstituted alkyl group having 1 to 30 carbonatoms, a substituted or unsubstituted alkoxy group having 1 to 30 carbonatoms, a substituted or unsubstituted aryl group having 6 to 40 carbonatoms, a trialkylsilyl group wherein the alkyl group has 1 to 20 carbonatoms and may have a substituent, an aryloxy group wherein the arylgroup has 6 to 40 carbon atoms and may have a substituent, a halogenatom, or a cyano group, provided that at least two of R₁₁ to R₂₃ eachrepresent a cyano group, a trifluoromethyl group or a fluorine atom andthat those of R₁₁ to R₂₃, which are adjacent to one another, may belinked together to form a ring structure;

wherein R₂₄ to R₃₉ each independently represent a hydrogen atom, asubstituted or unsubstituted alkyl group having 1 to 30 carbon atoms, asubstituted or unsubstituted alkoxy group having 1 to 30 carbon atoms, asubstituted or unsubstituted aryl group having 6 to 40 carbon atoms, atrialkylsilyl group wherein the alkyl group has 1 to 20 carbon atoms andmay have a substituent, an aryloxy group wherein the aryl group has 6 to40 carbon atoms and may have a substituent, a halogen atom, or a cyanogroup, provided that at least two of R₂₄ to R₃₉ each represent a cyanogroup, a trifluoromethyl group or a fluorine atom and that those of R₂₄to R₃₉ which are adjacent to one another, may be linked together to forma ring structure;

wherein R₄₀ to R₅₇ each independently represent a hydrogen atom, asubstituted or unsubstituted alkyl group having 1 to 30 carbon atoms, asubstituted or unsubstituted alkoxy group having 1 to 30 carbon atoms, asubstituted or unsubstituted aryl group having 6 to 40 carbon atoms, atrialkylsilyl group wherein the alkyl group has 1 to 20 carbon atoms andmay have a substituent, an aryloxy group wherein the aryl group has 6 to40 carbon atoms and may have a substituent, a halogen atom, or a cyanogroup, provided that at least two of R₄₀ to R₅₇ each represent a cyanogroup, a trifluoromethyl group or a fluorine atom and that those of R₄₀to R₅₇ which are adjacent to one another, may be linked together to forma ring structure; and

wherein R₅₈-R₆₁ independently represents hydrogen, fluorine, orsubstituents independently selected from nitrile (—CN), nitro (—NO₂),sulfonyl (—SO₂R), sulfoxide (—SOR), trifluoromethyl (—CF₃), ester(—CO-DR), amide (—CONHR or —CO—NRR′), substituted or unsubstituted aryl,substituted or unsubstituted heteroaryl, or substituted or unsubstitutedalkyl, where R and R′ include substituted or unsubstituted alkyl oraryl; or R₅₈ and R₅₉, or R₆₀ and R₆₁, combine form a ring structureincluding an aromatic ring, a heteroaromatic ring, or a non-aromaticring, and each ring is substituted or unsubstituted.
 12. The method ofclaim 1, wherein the organic electron acceptor is:


13. The method of claim 1, wherein the organic electron donor isselected from the group consisting of:


14. The method of claim 1, wherein the organic electron acceptor is:

and wherein the organic electron donor is selected from the groupconsisting of:


15. The method of claim 14, wherein the organic electron donor is:


16. The method of claim 1, wherein the solution process is spin coatingor inkjet printing.
 17. The method of claim 1, wherein the organicelectron acceptor and the organic electron donor are mixed at a moleratio of 1:1 or 2:1.
 18. The device of claim 1, wherein the insolubleorganic layer forms when the composition is heated at a temperature noless than about 100° C. and no more than about 250° C.
 19. A firstdevice comprising an organic light emitting device, further comprising:an anode; a cathode; and a first organic layer disposed between theanode and the cathode, wherein the first organic layer comprises anorganic electron acceptor; and an organic electron donor having theformula:

wherein A, B, and C are 5 or 6 membered cyclic or heterocyclic rings;wherein R_(A), R_(B), and R_(C) are independently selected from thegroup consisting of hydrogen, halogen, alkyl, alkoxy, amino, alkenyl,alkynyl, aryl and heteroaryl; and wherein R_(A), R_(B), and R_(C) areoptionally fused to A, B, and C; and wherein at least two of R_(A),R_(B), and R_(C) contain the structure:

wherein X and Y are independently 5 or 6 membered cyclic or heterocyclicrings; wherein R_(X) and R_(X) are independent selected from the groupconsisting of hydrogen, halogen, alkyl, alkoxy, amino, alkenyl, alkynyl,aryl and heteroaryl; wherein R_(X) and R_(Y) are optionally fused to Xand Y; wherein R_(X) and R_(Y) are optionally connected to A and B; andwherein the organic electron acceptor and the organic electron donorform an insoluble organic layer when the composition is heated.
 20. Thedevice of claim 19, wherein the organic electron acceptor and theorganic electron donor form a layer that is insoluble in a non-polarsolvent.